Feature batch: Projects, Recurrence, Group settings, Bug fixes

- Projects CRUD API + invite members
- Task recurrence (daily/weekly/monthly) with auto-creation
- Group time zones + GPS locations settings
- i18n fallback fix (no more undefined labels)
- UX: action buttons in one row
- Chat/Calendar: relative API URLs
- DB: task_assignments, projects tables, recurrence column

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/tasks/lib/i18n.tsx

@@ -22,14 +22,14 @@ const MESSAGES: Record<Locale, Messages> = { cs, he, ru, ua };
 
 const STORAGE_KEY = "taskteam_language";
 
-function getNestedValue(obj: unknown, path: string): string {
+function getNestedValue(obj: unknown, path: string): string | undefined {
   const keys = path.split(".");
   let current: unknown = obj;
   for (const key of keys) {
-    if (current == null || typeof current !== "object") return path;
+    if (current == null || typeof current !== "object") return undefined;
     current = (current as Record<string, unknown>)[key];
   }
-  return typeof current === "string" ? current : path;
+  return typeof current === "string" ? current : undefined;
 }
 
 interface I18nContextType {
@@ -75,7 +75,10 @@ export function I18nProvider({ children }: { children: ReactNode }) {
 
   const t = useCallback(
     (key: string): string => {
-      return getNestedValue(MESSAGES[locale], key);
+      const value = getNestedValue(MESSAGES[locale], key);
+      if (value !== undefined) return value;
+      // Fallback: return last segment of the key (the raw value) instead of "undefined"
+      return key.split(".").pop() || key;
     },
     [locale]
   );